Sectional floating roof and roof sections therefor



Feb. 3, 1970 J, c, THCMPSON ETAL' 3,493,143

SEGTIONAL FLOATING ROOF AND ROOF SECTIONS THEREFOR Filed Nov. 1.7. 1967 4 Sheets-Sheet 2 20 VAR/ABLE M 2 w B .0 LF 1. -l M q D N m m 8 m 8 5 0 u 6 H 5 5: M 0 w J 1970 J. c. THOMPSON ETAL 3,493,143

SECTIONAL FLOATING ROOF AND ROOF SECTIONS THEREFOR Filed Nov. 17, 1967 4 Sheets-Sheet s IQO , FIG; I0 H0 2 F I 6. l I

1L r 25/ I M N 25/ 22 I 1 2/ I I30 4 1 I30 17/ r l X L '70 I X I TT 120 L- Feb. 3, 1970 J. c. THOMPSON ETAL 3,493,143

SECTIONAL FLOATING ROOF AND ROOF SECTIONS THEREFOR Filed Nov. 17. 19s? 4 sheet -sheet 4 United States Patent 3,493,143 SECTIONAL FLOATING ROOF AND ROOF SECTIONS THEREFOR Joseph C. Thompson, Arlington Heights, and Milton W. Heisterberg, Homewood, 11]., assignors to General American Transportation Corporation, Chicago, Ill., a corporation of New York Filed Nov. 17, 1967, Ser. No. 683,962 Int. Cl. B65d 87/20 U.S. Cl. 220--26 21 Claims ABSTRACT OF THE DISCLOSURE There is disclosed a floating roof for use in a storage tank having an upstanding substantially cylindrical shell and posts supporting a fixed roof thereon, the floating roof comprising a plurality of like inner roof sections and a plurality of outer roof sections shaped and arranged to fill the space between an assembly of the inner roof sections and the associated shell; each roof section includes a continuous peripheral wall therearound and a bottom wall closing the area defined by the peripheral wall, the bottom wall having portions thereof spaced upwardly from the lower edges of the peripheral wall; the adjacent peripheral walls are joined as by riveting; a first flexible seal is supported upon the roof sections and extends outwardly therefrom and against the associated shell; and a second flexible seal is supported upon the roof sections about each of the posts.

The present invention is directed to a sectional floating roof for use in a storage tank, and to individual buoyant roof sections useful in forming such a floating roof.

It is an important object of the present invention to provide a floating roof for use in a storage tank having an upstanding substantially cylindrical shell, the floating roof comprising a plurality of inner roof sections substantially identical one to the other and individually buoyant, each of the inner roof sections including a pair of upstanding generally parallel side walls and a pair of upstanding generally parallel end walls joined to form a first continuous peripheral wall therearound and a first bottom wall closing the area defined by the first peripheral wall, the first bottom wall having portions thereof spaced upwardly from the lower edges of the side walls and the end walls to trap vapors in the space provided thereunder and to increase the stability of the inner roof section during flotation thereof, the inner roof sections being arranged substantially to fill the area defined by the associated shell with the first peripheral walls of each inner roof section belng (1 18- posed against the first peripheral walls of the ad acent 1nner roof sections, a plurality of outer roof sections disposed between the inner roof sections and the associated shell and being individually buoyant, each of the outer roof sections including a second continuous peripheral wall therearound and a second bottom wall closing the area defined by the second peripheral wall, the second bottom wall having portions thereof spaced upwardly from the lower edges of the second peripheral wall to trap vapors in the spaces provided thereunder to increase the stability of the outer roof section during flotation thereof, the outer roof sections being shaped and arranged substantially to fill the spaces between the inner roof sections and the associated shell, means securing the adjacent peripheral walls of the roof sections one to the other to hold the roof sections in the assembled positions thereof, and sealing means supported upon the roof sections and disposed between the roof sections and the associated shell to provide a vapor seal between the floating roof and the associated shell.

ice

In connection with the foregoing object, it is another object of the invention to provide a floating roof of the type set forth wherein the inner roof sections are substantially rectangular in shape and of standard construction, whereby material savings in cost and labor can be had by mass-production thereof and transportation thereof to the tank site for incorporation into a sectional floating roof of the present invention.

Another object of the invention is to provide a sectional floating roof of the type set forth requiring no special seal between the adjacent sections forming the roof, each of the sections being shaped and formed to be individually buoyant and stable and designed to trap vapors thereunder in an area defined by the peripheral wall and the bottom wall, whereby simple fasteners such as rivets may be used to join adjacent roof sections without special sealing structures therebetween.

Yet another object of the invention is to provide in a floating roof of the type set forth an improved structure for mounting the vapor seal between the floating roof and the associated shell, the mounting structure including a mounting plate formed from either a plurality or arcuate sections mounted on the roof sections or a plurality of straight sections mounted on the roof sections.

Still another object of the invention is to provide on a sectional floating roof of the type set forth an improved structure for providing a vapor seal between the floating roof and posts passing therethrough and supporting an associated stationary roof disposed thereabove.

Another object of the invention is to provide for the improved floating roof of the present invention an improved buoyant roof section including a pair of upstanding generally parallel side walls and a pair of upstanding end walls, the side walls and the end walls being joined to form a continuous peripheral wall therearound, and a bottom wall closing the area defined by the peripheral wall, the bottom wall having portions thereof spaced upwardly from the lower edges of the side walls and the end walls to trap vapors in the space provided thereunder and to increase the stability of the roof section during flotation thereof.

In connection with the foregoing object, it is another object of the invention to provide an improved buoyant roof section of more economical construction, wherein in one preferred form the bottom wall and the side walls are formed integral and are bent into the desired shape and are joined to the end wall as by welding and wherein in another preferred form the bottom wall is secured to the side walls directly as by welding.

A further object of the invention is to provide a standard roof section for use in forming a sectional floating roof of the type set forth, the standardroof section being adapted to be manufactured by mass-production tech nique, thereby to be economical in cost as well as economical in assembly with other roof sections to form a completed floating roof.

A still further object of the invention is to provide a buoyant outer roof section for use in forming a floating roof of the type set forth, the outer roof section being of the same lateral cross section as the standard roof section but having different lengths and on occasion nonparallel end walls, whereby to be advantageously useful in filling the spaces required to keep a generally circular assembly of roof sections.

Further features of the invention pertain to the particular arrangement of the roof sections and the assembly thereof into a floating roof, whereby the above-outlined and additional operating features thereof are attained.

The invention, both as to its organization and method of operation, together with further objects and advantages thereof, will best be understood by reference to the following specification taken in connection with the accompanying drawings, in which:

FIGURE 1 is a side elevational view of a covered storage tank having mounted therein a floating roof made in accordance with and embodying the principles of the present invention, a portion of the storage tank and a portion of the outer vapor seal being broken away better to illustrate the construction of the floating roof;

FIG. 2 is a fragmentary view in horizontal section on an enlarged scale through the tank of FIG. 1 along the line 22 thereof;

FIG. 3 is a perspective view on a further enlarged scale of one of the standard roof sections utilized in assembling the floating roof of FIGS. 1 and 2;

FIG. 4 is a perspective view with certain portions broken away of an outer roof section useful in forming the floating roof of FIGS. 1 and 2;

FIG. 5 is a view on a further enlarged scale in vertical section along the line 55 of FIG. 3 and illustrating the first preferred embodiment of the roof section of the present invention;

FIG. '6 is a View on a slightly reduced scale similar to FIG. 5 and showing a second preferred embodiment of the roof section of the present invention;

FIG. 7 is a view on a slightly reduced scale similar to FIG. 5 and showing a third preferred embodiment of the roof section of the present invention;

FIG. 8 is a plan view on a reduced scale of the standard roof section of FIG. 3 and illustrating the manner in which the various outer roof sections may be formed therefrom by changing the longitudinal length thereof and/or by changing the orientation of one of the end walls thereof;

FIG. 9 is a fragmentary plan view on a further enlarged scale with certain portions broken away showing an outer portion of the floating roof of FIG. 2;

FIG. 10 is a view on a further enlarged scale in vertical section along the line 1010 of FIG. 9;

FIG. 11 is a fragmentary plan view similar to FIG. 2 and illustrating an alternative structure for mounting the external vapor seal on the floating roof;

FIG. 12 is a further enlarged view in vertical section along the line 1212 of FIG. 9; I

FIG. 13 is a fragmentary view on an enlarged scale of the portion of the floating roof around one of the roof support posts passing therethrough; and

FIG. 14 is a view in vertical section along the line 14-14 in FIG. 13.

Referring to FIG. 1 of the drawings, there is illustrated a storage tank 20 of the floating roof type having a column supported fixed cone roof thereon and having disposed therein an internal floating roof 100 made in accordance with and embodying the principles of the present invention. The storage tank 20 is particularly adapted for storing liquids such as petroleum products that have a significant vapor pressure, the floating roof 100' being provided to trap and hold the vapors from the petroleum products to prevent escape thereof from the tank 20. Considering now the mechanical construction of the tank 20, there is provided an upstanding substantially cylindrical side wall or shell 21 having a generally cylindrical inner surface 22, the shell 21 being mounted upon a suitable base or floor 23 and carrying on the upper portion thereof a cone roof 24 which serves to cover the entire area bounded by the shell 21 and is fixedly secured thereto. As illustrated, the tank 20 has a diameter such that the cone roof 24 must be supported by a plurality of columns or posts 25 extending from the floor 23 upwardly to the underside of the fixed roof 24 for support thereof. There further is provided suitable inlet fixtures (not shown) and the usual outlet fixture 26 for adding lading to the tank 20 and for withdrawing lading therefrom. Finally, there is provided a manhole 27 having a conventional cover 28 associated therewith, whereby access may be had to the interior of the tank 20 for construction and repair thereof, the manhole typically having an internal diameter of about 20 inches.

As illustrated in FIG. 1, there is a body 3'0 of petroleum stored within the tank 20 and floating upon the upper surface 31 of the petroleum 30 is the floating roof for the purpose of maintaining any petroleum vapors adjacent to the liquid petroleum 30, thereby to prevent further volatilization of the liquid petroleum 30 and to prevent escape of the vaporized petroleum from beneath the floating roof 100 and out of the storage tank 20. To this end, the floating roof 100 extends over the entire surface of the petroleum 30 and moves vertically within the storage tank 20 as the level of the petroleum 30 within the tank 20 changes. In order to prevent the vapor loss referred to above, a first sealing arrangement 150 is provided between the floating roof 100 and the inner surface 22 of the shell 21, and a second sealing arrangement 170 is provided between the floating roof 100 and each of the supporting posts 25.

Considering now in detail the construction of the floating roof 100, particular reference being made to FIGS. 2 through 10 of the drawings, it will be seen from FIG. 2 that the floating roof 100 is made up from a plurality of roof sections, three distinct types of roof sections being provided including an inner standard roof section 100, an inner shortened roof section 120 and an outer roof section 130. It is an important feature of the present invention that each of the three types of roof sections named have the same basic cross section in a direction transverse to the longitudinal axes thereof, the differences among the roof sections residing in the lengths thereof and the disposition of the end walls thereof.

Referring to FIGS. 3, 5 and 8, there are illustrated the details of construction of the inner standard roof section 110. It will be noted that the roof section is generally rectangular in plan view and is also rectangular in the side and end views. In general, the roof section 110 comprises a peripheral wall, formed from a pair of generally upstanding parallel spaced-apart side walls 111 and a pair of generally upstanding parallel spaced-apart end walls 112 that extend between the side walls 111 and are suitably joined thereto as by welding to provide a continuous peripheral rectangular wall about the roof section 110. The area defined by and surrounded by the aforementioned peripheral wall is closed by a bottom wall of composite structure. More specifically, the bottom wall 115 includes a pair of rectangular longitudinally extending center portions 116 which extend between the end walls 112 and are secured thereto as by welding at the outer ends thereof. The inner edges of the center portions 116 are joined as at 114 and the outer edges have formed integral therewith and respectively depending therefrom side flanges 118, the outer longitudinal edges of the center portions 116 being joined to the upper edges of the respective side flanges 115 along longitudinally extending junctions 117. The lower edges of the side flanges 118 are joined to the lower edges of the side walls 111 by curved junctions 119, respectively, and the outer ends of the side flanges 118 are secured to the end walls 112 as by welding.

Referring to FIG. 5, it will be seen that the side walls 111 and the bottom walls 115, including the center portions 116 and the side flanges 118 are all preferably formed of a single rectangular sheet of material, such assheet metal, bent to provide the parts named in the relationship illustrated. More specifically, the junctions 117 are disposed well above the lower edges of the side walls 111 and only a short distance below the upper edges of the side walls 111, while the central junction 114 is disposed slightly below the junctions 117. The end walls 112 in this form of the invention are formed as rectangular plates of the same material as the other parts, for example, sheet metal, and are secured to the ends of the side walls 111 and the bottom wall 115 by welding, care being taken to provide a fluid-tight joint therebetween. When so constructed, it will be appreciated that a significant volume is provided below the bottom wall 115 and between the end walls 112, which volume is useful in the floatation of the roof section 110 upon the petroleum 30. More specifically, each of the roof sections 110 is individually buoyant, and preferably is designed so that the upper surface 31 of the petroleum upon which the roof section 110 floats will be arranged as illustrated in FIG. 5. It will be appreciated that a significant volume 113 is provided between the surface 31 and the bottom wall 115 for trapping of petroleum vapors therein, while the side walls 111 and the end walls 112 extend essentially normal to the surface 31 and with the upper edges of the walls disposed a good distance thereabove.

In view of the fact that the upper edges of the walls 111 and 112 are disposed well above the surface 21, assemblies of the roof sections 110 can be readily made and the individual roof sections, secured one to the other by means of rivets 140 passing through the upper portions of the walls 111 and 112, all as is illustrated in FIG. 10. Inasmuch as the rivets 140 and the holes associated therewith are disposed well above the surface 31 of the petroleum 30, no special sealing structure must be provided therefor. Further, since the outer surfaces of the side walls 111 and the end walls 112 are substantially flat and planar, the fiat surfaces will tightly bear against the adjacent such surfaces and will be held in close contact by the rivets 140, whereby to eliminate the necessity of any gaskets or sealing structure therebetween, or in fact between the roof sections 110 generally.

The dimensions of the standard roof section 110 are chosen so that the sections may be readily handled by workmen during the construction or repair of the floating roof 100, and more specifically, the dimensions are such that the standard roof sections 110 can be passed through the manhole 27, thus allowing construction and repair of the floating roof 100 after the tank 20 has been fully erected. In a typical construction of the standard roof section 110, the length thereof, i.e., the length of the side walls 111, is 16 feet, the width of the roof section 110, i.e., the length of the end walls 112 is 18 inches, while the vertical extent of the walls 111 and 112 is 4 inches. A standard roof section 110 having such dimensions can be readily passed through the manhole 27 and lowered into the storage tank 20. It will be understood that the individual roof sections may be temporarily supported on a frame during assembly of the roof 100 in order to provide the proper level of each of the roof sections, or 4 to 6 inches of water may be introduced into the tank so that the individual buoyant roof sections can be floated thereon and thereafter assembled to provide the completed roof 100.

In accordance with the present invention, as many as possible of the standard roof sections 110 are utilized in forming the roof 100 since the standard roof sections 110 can be in effect mass-produced, thus accomplishing significant economies in the manufacture thereof. Further to effect economies in the manufacture of the several types of roof sections, the same cross section illustrated in FIG. 5 is provided in each, i.e., the same cross section including the side walls 111, the bottom wall center portions 116 and the side flanges 118. As is illustrated in FIG. 8, each of the inner shortened roof sections 120 is essentially like the standard roof section 110 except that the length thereof is less, this being diagrammatically illustrated by the dashed line showing of the end Wall 122. The roof sections 120 are utilized to fill rectangular areas which are shorter than the standard roof section 110.

There is however a special problem encountered on the periphery of the roof 110 inasmuch as the roof 100 is essentially circular so as to conform to the circular shape of the tank shell 21. So as to approximate a circular outer periphery for the tank 100, a plurality of outer roof sections 130 are provided, the outer roof sections 130 having the same lateral cross section as the roof sections 110 and 120 and varying therefrom only in that one of the end walls designated 132A in FIGS. 4 and 8 is disposed at an acute angle with respect to the normal end wall 112 or 122 as the case may be, the angle being identified by the letter beta in FIG. 8. In order more nearly to approximate the desired circular outline of the roof 100, the lengths of the outer roof sections 130 are varied as is the angle beta for the annular disposition of the end Wall 132A. However, it has been found that only a very few different forms of the outer roof sections 130 are required, namely about a half dozen, in order to provide a good approximation of a circular outline for the roof (see FIG. 2), whereby again substantial economies in manufacture are obtained.

It is to be noted that throughout the drawings, the several parts of the inner shortened roof section have had applied thereto numerals in the 120 series that correspond to the numerals in the 110 series of like parts for the standard roof section 110; and likewise the several parts of the outer roof section have had applied thereto numerals in the 130 series that correspond to the numerals in the 110 series of like parts for the standard roof section 110. Furthermore, the same type of rivet is useful in joining all of the roof sections 110, 120 and 130, the rivets 140 preferably being pop rivets. It is further pointed out with reference to FIG. 4 that the end Wall 132A has an inturned flange 132B on the upper edge thereof that is useful in attaching the shell seal structure as will be explained more fully hereinafter.

There are illustrated in FIGS. 6 and 7 alternative cross sections for the standard roof section 110. Referring first to FIG. 6, there is shown a first modification of the standard roof section identified by the numeral 210 and including a pair of generally upstanding parallel side walls 211 that are joined by a bottom wall 215. The bottom Wall 215 comprises two center portions 216 that are joined along the inner edges thereof as at 214 and extend outwardly and upwardly therefrom to points spaced just slightly below the upper edges of the side walls, respectively, and are secured thereto as by welding at points 219. It will be understood that generally rectangular walls (not shown) are provided to close and connect the ends of the side walls 211 to provide a continuous peripheral wall and a buoyant fluid-tight roof section 210. When the roof section 210 if floated upon the petroleum having the surface as at 31, it will be seen that a vapor trapping space 213 is provided between each of the side walls 211 and the adjacent center portion 216.

Referring now to FIG. 7, there is shown another modification of the cross section useful in producing a standard roof section, this standard roof section being designated by the numeral 310. A pair of generally upstanding parallel side walls 311 are provided that are connected by a bottom wall 315. The bottom wall 315 includes two longitudinally extending substantially rectangular center :portions 316 which are joined along the inner longitudinally extending edges as at 314 and extend outwardly and upwardly therefrom and carry on the outer edges thereof the depending flanges 318 joined thereto as at 317. As illustrated, the side flanges 318 are disposed parallel to the adjacent side wall 311 and are disposed fiush thereagainst and further secured thereto as by welding at 319. For convenience in manufacture, the center portions 316 and the flanges 318 are formed from a single rectangular sheet of metal bent to provide the parts and shapes illustrated. It further Will be understood that the ends of the side wall 311 are connected and closed by end walls (not shown) which are secured thereto in a fluid-tight manner so as to provide a buoyant standard roof section 310.

A typical pattern for assembling a plurality of the standard roof sections 110 with the required shortened roof sections 120 and outer roof sections 130 to provide a generally circular assembly is illustrated in FIGS. 2 and 10. It will be noted that as many as possible of the standard roof sections 110 and the shortened roof sections 120 are used, this resulting in a marked economy in manufacture and construction since these sections are more economically produced and assembled. However, to provide a substantially circular outline for the roof 100, a plurality of and a number of difierent varieties of the outer roof sections 130 are provided. As is best seen in FIGS, 9 and 10, the several roof sections are all secured by the rivets 140 at frequent intervals along the adjacent side walls and end walls so as completely to fill the area of the roof 100 so that there are no voids or spaces therein. The individually buoyant roof sections when assembled as illustrated form a vapor-tight liquid seal around the edges, whereby no gaskets or seals are provided between the adjacent roof sections. The lurality of side walls and end walls joined one to another also provides stiffness for the floating roof 100. It will be understood that as shipped from the factory, the several roof sections have imperforate side and end walls, the necessary holes for the rivets 140 being punched in the field as a part of the assembly operation. The assembled roof 100 is substantially lighter in weight than the floating roofs commonly used heretofore.

The outer periphery of the thus assembled roof sections is spaced a distance away from the inner surface 22 of the shell 21, whereby it is necessary and desirable to provide the outer or shell seal structure 150 that extends around the outer periphery of the roof 100 and seals the area disposed bewteen the outer periphery of the roof 100 and the inner surface 22 of the shell 21. Re-

ferring to FIGS. 2, 9 and 12, there is illustrated a first preferred form of such a sealing structure which includes a generally annularly shaped and horizontally disposed mounting plate 151 extending completely around the periphery of the roof 100 and fixedly secured thereto. Preferably, the mounting plate 151 is provided in the form of several individual arcuate sections which are suitably secured to the outer roof sections 130, and specifically to the mounting flanges 132B thereon, as by rivets 140. The outer periphery of the mounting plate 151 carries an upstanding annular wall 152 secured to the mounting plate 151 as by welding at 153. Mounted on the'wall 152 is a sealing element 160 which is in the form of a substantially annular resilient member arranged in the annular space between the shell 21 and the wall 152 and located above the upper level 31 of the stored petroleum 30. The sealing element 160 more specifically formed of a body of flexible and resilient material, the preferred material being an expanded synthetic organic plastic resin, such for example as a copolymer of butadiene and acylonitrile resins, suitable resins being that sold under the trademark Buna N or that sold under the trademark Rubatex, or the equivalent.

Preferably the sealing element 160 is formed as a continuous extrusion of the resin shaped to provide a top wall 161 and a bottom wall 162 that converge radially outwardly and provide a thickened juncture 163 having a bearing surface 165 that is disposed in sliding and sealing engagement with the tank shell 21, and specifically the inner surface 22 thereof. Since the completed sealing element 160 is actually annular in shape, relatively short sections having the extruded shape of FIG. 12 are cemented in place during the construction of the floating roof 100 in the field to provide a continuous annular ring which at any point has a cross section along a diameter of the roof 100 of the shape generally illustrated in FIG. 12. It will be understood that before engagement of the bearing surface 165 with the tank shell 21, the top wall 161 of the sealing element 160 is arranged substantially horizontally, while the bottom wall 162 extends outwardly and upwardly toward the juncture 163 with the top wall 161. The top wall 161 extends radially inwardly and over the upper edge of the wall 152 and carries on the inner edge thereof a first mounting flange 166 which is disposed substantially normal to the top wall 161 and extends downwardly along the inner surface of the wall 152. The inner edge of the bottom wall 162 carries a second mounting flange 167 integral therewith and extending upwardly therefrom, the mounting flange 167 being disposed against the outer surface of the wall 152 and substantially parallel to the first mounting flange 166 and disposed in lateral alignment therewith. The sealing element 160 further comprises a pair of spaced-apart webs 168 and 169, the web 168 being disposed outwardly toward but spaced from the juncture 163 between the wall 161 and the wall 162 and is disposed substantially normal to the top wall 161, while the reinforcing web 169 is disposed toward but spaced from the mounting flanges 166167 and is also disposed substantially normal to the top wall 161. The reinforcing webs 168 and 169 provide a desired degree of rigidity in the sealing element 160 and in effect provide a relative stifl? body having on the outer annular edge thereof the bearing surface 165 and having on the inner annular edges thereof the mounting flanges 166 and 167.

Fastener structure is provided to mount the sealing element 160 upon the wall 152 of the floating roof so as to hold the bearing surface 165 of the sealing element 160 disposed in sliding and sealing engagement with the tank shell, thus to seal the annular space between the tank shell and the roof 100 above the surface of the stored petroleum 30. To this end aligned holes are provided at regular intervals through the wall 152 and the mounting flanges 166-167. There is provided, against the outer surface of the mounting flange 167 a clamp bar 154 having openings therein in alignment with the holes in the flange 167 and with threaded nuts 155 arranged in registry with those holes. A washer bar 156 is provided against the inner surface of the mounting flange 166 and having openings therein in alignment with the holes in the flange 166, the washer bar 156 having a plurality of washers 157 suitably secured thereto as by welding and having openings therein in alignment with the openings in the washer bar 156 Finally, there is provided a bolt having a threaded shank 146 pointed at the outer end thereof, the shank 146 of the bolt 145 extending through the aligned openings in the associated washer 157 and the washer bar 156, and through the associated aligned holes in the wall 152 and the mounting flanges 166-167, and through the associated opening in the clamp bar 154- and threadedly engaging the associated nut 155 on the clamp bar 154. In this manner, the bolt 14-5 serves to clamp the mounting flanges 166 and 167 against the wall 152 and between the clamp bar 154 and the washer bar 156. It will be understood that the clamp bar 154 and the washer bar 156 are formed as generally rectangular pieces of metal that are then curved to conform to, and to have a radius of curvature substantially equal to, the radius of curvature of the wall 152, preferably the bars 154 and 156 having convenient lengths, such as for example three feet, whereby a plurality of the bars 154 and 156 is provided around the periphery of the floating roof 100, the nuts 155 and the washers 157 preferably being disposed approximately every nine inches therealong.

It will be appreciated that other forms of sealing elements 160 and other forms of sealing structures 150 may be used in place of those illustrated, it only being required that the structure and sealing element provide the necessary tight seal between the floating roof 100 and the tank shell 21.

In fact there is shown in FIG. 11 of the drawings a modification of the sealing structure 150, this modification being identified by the numeral 250. As illustrated, a plurality of straight mounting plates 251 has been substituted for the curved mounting plates 151, the sealing element 160 being mounted on the mounting plates 251. It will be understood that the straight mounting plates 251 are in fact mounted by means of rivets upon the 9 mounting flanges 132B f the several outer roof sections 130.

There further are provided between the floating roof 100 and the several supporting posts the post seal structures 170. Referring to FIGS. 2, 13 and 14, the details of the post seal structures 170 will be described. First of all it is pointed out that a generally rectangular space is provided around each of the posts 25 by spacing the roof sections 110 and 120 apart from one another as is best seen in FIG. 13. There is provided about each of the posts 25 a cover plate 171 which may preferably be formed in sections and the sections assembled about the posts 25, the several sections being secured as by welding to provide a unitary cover plate 171 as illustrated having an opening 171A centrally thereof receiving the associated post 25 therethrough. A continuous peripheral wall is also provided around the rectangular opening formed by the adjacent roof sections, the peripheral wall being formed by a pair of generally upstanding parallel side walls 172 and a pair of generally upstanding parallel end walls 173 joining the outer ends of the side walls 172 and being welded thereto and to the underside of the cover plate 171 as at 174. The side walls 172 and end walls 173 form a dip ring, the outer surfaces of which bear against the adjacent walls of the adjacent roof sections and are secured thereto so as to provide a fluid-tight seal therebetween. There further is mounted on the upper side of the cover plate 171 a rubber sealing element 175 which has an opening 176 therein that is slightly smaller in diameter than the diameter of the associated post 25, the sealing element 175 also having a slit 177 extending from the edge thereof inwardly to the opening 17 6 so as to permit assembly of the sealing element 175 about the post 25. A plurality of rivets 178 serves to mount the sealing element 175 upon the cover plate 171 in the position shown with the material defining the periphery of the opening 176 snugly engaging the outer surface of the associated post 25.

With the outer seal structure 150 and the several post seal structures 170 in position, the floating roof 100 is not only fluid-tight, but is also vapor-tight, whereby to trap and hold the petroleum vapors that are always present above the stored petroleum 30. In this manner, the escape of the petroleum vapor from the storage tank 20 is positively prevented, thus to prevent loss of the petroleum from the tank 20. Furthermore, the several sealing elements 160 and 175 maintain the sealing contact with the surfaces of the shell 21 and the posts 25, respectively, as the floating roof 100 rises and falls in accordance with the addition and withdrawal of the petroleum to and from the storage tank 20.

From the above it will be seen that there has been provided an improved sectional floating roof 100 and improved roof sections 110, 120 and 130 therefor which fulfill all of the objects and advantages set forth above.

While there have been illustrated and described what are presently considered to be certain preferred embodiments of the invention, it will be understood that various modifications may be made therein which fall within the true spirit and scope of the invention.

What is claimed is:

1. A floating roof for use in a storage tank having an upstanding substantially cylindrical shell, said floating roof comprising a plurality of inner roof sections substantially identical one to the other and being individually buoyant, each of said inner roof sections including a pair of upstanding generally parallel side walls and a pair of upstanding generally parallel end walls joined to form a first continuous peripheral wall therearound and a first bottom wall closing the area defined by said first peripheral wall, said first bottom wall having portions only thereof spaced upwardly from the lower edges of said side walls and said end walls defining a plurality of downwardly opening pockets to trap vapors in the space provided thereunder and to increase the stability of said in ner roof section during flotation thereof, said inner roof sections being arranged substantially to fill the area defined by the associated shell with said first peripheral walls of each inner roof section being disposed against the first peripheral walls of the adjacent inner roof sections, a plurality of outer roof sections disposed between said inner roof sections and the associated shell and being individually buoyant, each of said outer roof sections including a second continuous peripheral wall therearound and a second bottom wall closing the area defined by said second peripheral wall, said second bottom wall having portions only thereof spaced upwardly from the lower edges of said second peripheral wall defining a plurality of downwardly opening pockets to trap vapors in the spaces provided thereunder and to increase the stability of said outer roof section during flotation thereof, said outer roof sections being shaped and arranged substantially to fill the spaces between said inner roof sections and the associated shell, means securing the adjacent peripheral walls of said roof sections one to the other to hold said roof sections in the assembled positions thereof, and sealing means supported upon said roof sections and disposed between said roof sections and the associated shell to provide a vapor seal between said floating roof and the associated shell.

2. The floating roof set forth in claim 1, wherein said inner roof sections are substantially rectangular in shape with said side walls being disposed normal to said end walls.

3. The floating roof set forth in claim 1, wherein said means securing the adjacent peripheral walls comprises a plurality of rivets extending therethrouglh adjacent to the upper edges thereof.

4. A floating roof for use in a storage tank having an upstanding substantially cylindrical shell, said floating roof comprising a plurality of inner roof sections substantially identical one to the other and being individually buoyant, each of said inner roof sections including a pair of upstanding generally parallel side walls and a pair of upstanding generally parallel end walls joined to form a first continuous peripheral wall therearound and a first bottom wall closing the area defined by said first peripheral wall, said first bottom wall having portions only thereof spaced upwardly from the lower edges of said side walls and said end walls defining a plurality of downwardly opening pockets to trap vapors in the space provided thereunder and to increase the stability of said inner roof section during floatation thereof, said inner roof sections being arranged substantially to fill the area defined by the associated shell with said first peripheral walls of each inner roof section being disposed against the first peripheral walls of the adjacent inner roof sections, a plurality of outer roof sections disposed between said inner roof sections and the associated shell and being individually buoyant, each of said outer roof sections including a second continuous peripheral wall therearound and a second bottom wall closing the area defined by said second peripheral wall, said second bottom wall having portions only thereof spaced upwardl from the lower edges of said second peripheral wall defining a plurality of downwardly opening pockets to trap vapors in the spaces provided thereunder and to increase the stability of said outer roof sections during flotation thereof, said outer roof sections being shaped and arranged substantially to fill the spaces between said inner roof sections and the associated shell, means securing the adjacent peripheral walls of said roof sections one to the other to hold said roof sections in the assembled positions thereof, a mounting plate secured to the outer ends of the outermost ones of said roof sections adjacent to the associated shell, and a sealing element mounted on said mounting plate and extending to the associated shell and closing the space therebetween to provide a vapor seal between said floating roof and the associated shell.

5. The floating roof set forth in claim 4, wherein said mounting plate is formed from a plurality of arcuate sections.

6. The floating roof set forth in claim 4, wherein said mounting plate is formed from a plurality of straight sections.

7. The floating roof set forth in claim 4, wherein the upper edges of the peripheral walls of said outer roof sections carry inwardly directed flanges for securing said mounting plate to said roof sections.

8. A floating roof for use in a storage tank having an upstanding substantially cylindrical shell provided with a stationary roof and a plurality of upstanding posts supporting the stationary roof centrally thereof, said floating roof comprising a plurality of inner roof sections substantially identical one to the other and being individually buoyant, each of said inner roof sections including a pair of upstanding generally parallel side walls and a pair of upstanding generally parallel end walls joined to form a first continuous peripheral wall therearound and a first bottom wall closing the area defined by said first peripheral wall, said first bottom wall having portions only thereof spaced upwardly from the lower edges of said side walls and said end walls defining a plurality of downwardly opening pockets to trap vapors in the space provided thereunder and to increase the stability of said inner roof section during flotation thereof, said inner roof sections being arranged substantially to fill the area defined by the associated shell and around the associated posts with said first peripheral walls of each inner roof section being disposed against the first peripheral walls of the adjacent inner roof sections, a plurality of outer roof sections disposed between said inner roof sections and the associated shell and being individually buoyant, each of said outer roof sections including a second continuous peripheral wall therearound and a second bottom wall closing the area defined by said second peripheral wall, said second bottom wall having portions only thereof spaced upwardly from the lower edges of said second peripheral wall to trap vapors in the spaces provided thereunder and to increase the stability of said outer roof section during flotation thereof, said outer roof sections being shaped and arranged substantially to fill the spaces betwene said inner roof sections and the associated shell, means securing the adjacent peripheral walls of said roof sections one to the other to hold said roof sections in the assembled positions thereof, first sealing means supported upon said roof sections and disposed between said floating roof and the associated shell, and a plurality of second sealing means corresponding in number to the associated posts and supported upon said roof sections and disposed between said roof sections and the associated posts to provide a vapor seal between said floating roof and the associated posts.

9. The floating roof set forth in claim 8, wherein each of said second sealing means includes a cover plate having an opening centrally thereof for receiving an associated post therethrough and extending outwardly over the peripheral walls of the adjacent roof section and secured thereto, a peripheral wall mounted on said cover plate and extending downwardly therefrom and disposed against the peripheral walls of the surrounding roof sections, and a resilient sealing element mounted on said cover plate and surrounding the associated post and bearing thereagainst to provide a seal therearound.

10. A buoyant outer roof section for use in forming a floating roof for a storage tank having an upstanding substantially cylindrical shell, said outer roof section including a pair of upstanding generally parallel rectangular side walls and a pair of upstanding rectangular end walls, said side walls and said end walls being joined to form a continuous peripheral wall therearound, a bottom wall closing the area defined by said peripheral wall, said bottom wall having portions only thereof spaced upwardly from the lower edges of said side walls and said end walls defining a plurality of downwardly opening pockets to trap vapors in the space provided thereunder and to increase the stability of said outer roof section during flotation thereof, and a mounting flange disposed on the upper edge of said end wall adapted to be disposed toward the adjacent shell, said mounting flange extending inwardly and overlying a portion of said bottom wall for mounting a sealing structure thereon,

11. A floating roof for use in a storage tank having an upstanding substantially cylindrical shell, said floating roof comprising a plurality of inner roof sections substantially identical one to the other and being individually buoyant, each of said inner roof sections including a pair of upstanding generally parallel side walls and a pair of upstanding generally parallel end walls joined to form a first continuous peripheral wall therearound and a first bottom wall closing the area defined by said first peripheral wall, said first bottom wall including a pair of longitudinally extending rectangular center portions joined along the longitudinally extending inner edges thereof and centrally of said first bottom wall, said center portions being inclined upwardly from said inner edges and having the longitudinally extending outer edges thereof joined to the adjacent one of said side walls to trap vapors in the space provided under said first bottom wall and to increase the stability of said inner roof section during flotation thereof, said inner roof sections being arranged substantially to fill the area defined by the associated shell with said first peripheral walls of each inner roof section being disposed against the first peripheral walls of the adjacent inner roof sections, a plurality of outer roof sections, disposed between said inner roof sections and the associated shell and being individually buoyant, each of said outer roof sections including a second continuous peripheral wall therearound and a second bottom wall closing the area defined by said second peripheral wall, said second bottom wall having portions thereof spaced upwardly from the lower edges of said second peripheral wall to trap vapors in the spaces provided thereunder and to increase the stability of said outer roof sections during flotation thereof, said outer roof sections being shaped and arranged substantially to fill the spaces between said inner roof sections and the associated shell, means securing the adjacent peripheral walls of said roof sections one to the other to hold said roof sections in the assembled positions thereof, and sealing means supported upon said roof sections and disposed between said roof sections and the associated shell to provide a vapor seal between said floating roof and the associated shell.

12. A floating roof for use in a storage tank having an upstanding substantially cylindrical shell, said floating roof comprising a plurality of inner roof sections substantially identical one to the other and being individually buoyant, each of said inner roof sections including a pair of upstanding generally parallel side walls and a pair of upstanding generally parallel end walls joined to form a first continuous peripheral wall therearound and a first bottom wall closing the area defined by said first peripheral wall, said first bottom wall including a pair of longitudinally extending rectangular center portions joined along the longitudinally extending inner edges thereof and centrally of said first bottom wall, said center portions being inclined upwardly from said inner edges and having side flanges respectively on the longitudinally extending outer edges thereof extending downwardly and joined to the lower edges of the associated side walls to trap vapors in the space provided under said first bottom wall and to increase the stability of said inner roof section during flotation thereof, said inner roof sections being arranged substantially to fill the area defined by the associated shell with said first peripheral walls of each inner roof section being disposed against the first peripheral walls of the adjacent inner roof sections, a plurality of outer roof sections disposed between said inner roof sections and the associated shell and being individually buoyant,

each of said outer roof sections including a second continuous peripheral wall therearound and a second bottom wall closing the area defined by said second peripheral wall, said second bottom wall having portions thereof spaced upwardly from the lower edges of said second peripheral wall to trap vapors in the spaces provided thereunder and to increase the stability of said outer roof section during flotation thereof, said outer roof sections being shaped and arranged susbtantially to fill the spaces between said inner roof sections and the associated shell, means securing the adjacent peripheral Walls of said roof sections one to the other to hold said roof sections in the assembled positions thereof, and sealing means supported upon said roof sections and disposed between said roof sections and the associated shell to provide a vapor seal between said floating roof and the associated shell.

13. The :floating roof set forth in claim 12, wherein said center portions and said side flanges and said side walls are formed from a single sheet of material bent to provide the parts mentioned, said end walls being joined to the other parts by Welding.

14. A floating roof for use in a storage tank having an upstanding substantially cylindrical shell, said floating roof comprising a plurality of inner roof sections substantially identical one to the other and being individually buoyant, each of said inner roof sections including a pair of upstanding generally parallel side walls and a pair of upstanding generally parallel end walls joined to form a first continuous peripheral wall therearound and a first bottom wall closing the area defined by said first peripheral wall, said first bottom wall including a pair of longitudinally extending rectangular center portions joined along the longitudinally extending inner edges thereof and centrally of said first bottom wall, said center portions being inclined upwardly from said inner edges and having the longitudinally extending outer edges thereof joined to the adjacent one of said side walls adjacent to the upper edge thereof to trap vapors in the space provided under said first bottom wall and to increase the stability of said inner roof section during flotation thereof, said inner roof sections being arranged substantially to fill the area defined by the associated shell with said first peripheral walls of each inner roof section being disposed against the first peripheral walls of the adjacent inner roof sections, a plurality of outer roof sections disposed between said inner roof sections and the associated shell and being individually buoyant, each of said outer roof sections including a second continuous peripheral wall therearound and a second bottom wall closing the area defined by said second peripheral wall, said second bottom wall having portions thereof spaced upwardly from the lower edges of said second peripheral wall to trap vapors in the spaces provided thereunder and to increase the stability of said outer roof section during flotation thereof, said outer roof sections being shaped and arranged substantially to fill the spaces between said inner roof sections and the associated shell, means securing the adjacent peripheral walls of said roof sections one to the other to hold said roof sections in the assembled positions thereof, and sealing means supported upon said roof sections and disposed between said roof sections and the associated shell to provide a vapor seal between said floating roof and the associated shell.

15. A floating roof for use in a storage tank having an upstanding substantially cylindrical shell, said floating roof comprising a plurality of inner roof sections substantially identical one to the other and being individually buoyant, each of said inner roof sections including a pair of upstanding generally parallel side walls and a pair of upstanding generally parallel end walls joined to form a first continuous peripheral wall therearound and a first bottom wall closing the area defined by said first peripheral Wall, said first bottom wall including a pair of longitudinally extending rectangular center portions joined along the longitudinally extending inner edges thereof and centrally of said first bottom wall, said center portions being inclined upwardly from said inner edges and having on the longitudinally extending outer edges thereof depending side flanges, and means joining the junctures between said center portions and the associated side flanges to the adjacent side wall adjacent to the upper edge thereof, to trap vapors in the space provided under said first bottom wall and to increase the stability of said inner roof section during flotation thereof, said inner roof sections being arranged substantially to fill the area defined by the associated shell with said first peripheral walls of each inner roof section being disposed against the first peripheral walls of the adjacent inner roof sections, a plurality of outer roof sections disposed between said inner roof sections and the associated shell and being individually buoyant, each of said outer roof sections including a second continuous peripheral wall therearound and a second bottom wall closing the area defined by said second peripheral wall, said second bottom wall having portions thereof spaced upwardly from the lower edges of said second peripheral wall to trap vapors in the spaces provided thereunder and to increase the stability of said outer roof section during flotation thereof, said outer roof sections being shaped and arranged substantially to fill the spaces between said inner roof sections and the associated shell, means securing the adjacent peripheral walls of said roof sections one to the other to hold said roof sections in the assembled positions thereof, and sealing means supported upon said roof sections and disposed between said roof sections and the associated shell to provide a vapor seal between said floating roof and the associated shell.

16. A floating roof for use in a storage tank having an upstanding substantially cylindrical shell, said floating roof comprising a plurality of inner roof sections substantially identical one to the other and being individually buoyant, each of said inner roof sections including a pair of upstanding generally parallel side walls and a pair of upstanding generally parallel end Walls joined to form a first continuous peripheral wall therearound and a first bottom Wall closing the area defined by said first peripheral Wall, said first bottom wall having portions thereof spaced upwardly from the lower edges of said side walls and said end wall to trap vapors in the space provided thereunder and to increase the stability of said inner roof section during flotation thereof, said inner roof sections being arranged substantially to fill the area defined by the associated shell With said first peripheral walls of each inner roof section being disposed against the first peripheral walls of the adjacent inner roof sections, a plurality of outer roof sections disposed between said inner roof sections and the associated shell and being individually buoyant, each of said outer roof sections including a second continuous peripheral wall therearound and a second bottom wall closing the area defined by said second peripheral wall, said second bottom wall having portions thereof spaced upwardly from the lower edges of said second peripheral wall to trap vapors in the spaces provided thereunder and to increase the sta bility of said outer roof section during flotation thereof, said outer roof sections being shaped and arranged substantially to fill the spaces between said inner roof sections and the associated shell, means securing the adjacent peripheral walls of said roof sections one to the other to hold said roof sections in the assembled positions thereof, a mounting plate secured to the outer ends of the outermost ones of said roof sections adjacent to the associated shell, said mounting plate including an upstanding substantially cylindrical wall structure spaced radially inwardly from the associated shell and defining an up standing substantially annular space therebetween, and a sealing element mounted on said mounting plate and extending to the associated shell and closing the space therebetween to provide a vapor seal between said floating roof and the associated shell, said sealing element having a body tapering from a base portion disposed adjacent to said cylindrical wall structure toward a hearing surface disposed in sliding sealing engagement with the associated shell, a top flange extending inwardly from the edges of said body and over the upper edge of said wall structure, a first mounting flange integral with the inner edge of said top flange and extending downwardly along the inner surface of said wall structure, a second mounting flange integral with said base and extending along the outer surface of said wall structure and substantially parallel to said first mounting flange and disposed in lateral alignment therewith, and fastener means interconnecting said first and second mounting flanges and said wall structures to mount said sealing element upon said wall structure with the bearing surface of said sealing element disposed in sliding sealing engagement with the associated shell.

17. A buoyant roof section for use in forming a floating roof for a storage tank, said roof section including a pair of upstanding generally parallel side walls and a pair of upstanding end walls, said side walls and said end walls being joined to form a continuous peripheral wall therearound, and a bottom Wall closing the area defined by said peripheral wall, said bottom wall including a pair of longitudinally extending center portions joined along the longitudinally extending inner edges thereof and centrally of said bottom wall, said center portions being inclined upwardly from said inner edges and having the longitudinally extending outer edges thereof joined to the adjacent one of said side walls to trap vapors in the space provided under said first bottom wall and to increase the stability of said roof section during flotation thereof.

18. A buoyant roof section for use in forming a floating roof for a storage tank, said roof section including a pair of upstanding generally parallel side walls and a pair of upstanding end Walls, said side walls and said end walls being joined to form a continuous peripheral wall therearound, and a bottom wall closing the area defined by said peripheral wall, said bottom wall including a pair of longitudinally extending center portions joined along the longitudinally extending inner edges thereof and centrally of said bottom wall, said center portions being inclined upwardly from said inner edges and having side flanges respectively on the longitudinally extending outer edges thereof extending downwardly and joined to the lower edges of the associated side walls to trap vapors in the space provided under said first bottom wall and to increase the stability of said roof section during flotation thereof.

19. The buoyant roof section set forth in claim 18, wherein said center portions and said side flanges and said side walls are formed from a single sheet of material bent to provide the parts mentioned, said end walls being joined to the other parts by welding.

20. A buoyant roof section for use in forming a floating roof for storage tank, said roof section including a pair of upstanding generally parallel side walls and a pair of upstanding end walls, said side walls and said end walls being joined to form a continuous peripheral wall therearound, and a bottom wall closing the area defined by said peripheral wall, said bottom wall including a pair of longitudinally extending center portions joined along the longitudinally extending inner edges thereof and centrally of said bottom wall, said center portions being inclined upwardly from said inner edges and having the longitudinally extending outer edges thereof joined to the adjacent one of said side walls adjacent to the upper edge thereof to trap vapors in the space provided under said first bottom wall and to increase the stability of said roof section during flotation thereof.

21. A buoyant roof section for use in forming a floating roof for a storage tank, said roof section including a pair of upstanding generally parallel side walls and a pair of upstanding end walls, said side walls and said end walls being joined to form a continuous peripheral wall therearound, and a bottom wall closing the area defined by said peripheral wall, said bottom wall including a pair of longitudinally extending rectangular center portions joined along the longitudinally extending inner edges thereof and centrally of said bottom wall, said center portions being inclined upwardly from said inner edges and having on the longitudinally extending outer edges thereof depending side flanges, and means joining the junctures between said center portions and the associated side flanges to the adjacent side wall adjacent to the upper edge thereof to trap vapors in the space provided under said first bottom wall and to increase the stability of said roof section during flotation thereof.

References Cited UNITED STATES PATENTS 1,493,344 5/ 1924 Huff. 1,639,625 8/1927 Afonin 22026 1,674,039 6/1928 Glass 22026 2,804,228 8/ 1957 Hartley 22026 2,973,113 2/1961 Fino. 3,106,310 10/1963 Scherer. 3,134,501 5/1964 Bodley. 2,750,067 6/1956 Wiggins 22026 FOREIGN PATENTS 1,382,329 11/1964 France.

JOSEPH R. LECLARE, Primary Examiner I. R. GARRETT, Assistant Examiner 

